Rheostat



(No Model.)

T. W. SHELTON.

RHEOSTAT.

No, 530,727. Patented Dec. 11, 1894.

120;: zw aewk. /4MM gww i270 UNITED STATES PATENT OFFICE.

THOMAS WV. SHELTON, OF ST. LOUIS, MISSOURI.

RH EOSTAT.

SPECIFICATION forming part of Letters Patent No. 530,727, dated December 11, 1 894.

Application filed August 20,1894- Serlal No. 520,785. (No model.)

.To all whom it may concern.-

Beit known that I, THOMAS W'. SHELTON, of the city of St. Louis, State of Missouri, have invented certain new and useful Improvements in Rheostats, of which the following is a full, clear, and exact description, reference being had to the accompanying drawings, forming a part hereof.

My invention relates to an improved rheostat, and consists in certain novel features of construction that will be herein after described and claimed.

The object of my invention is to construct a rheostat that will be inexpensive and possess superior advantages in point of simplicity, durability and general efficiency.

Referring to the drawings: Figure 1 is a longitudinal sectional View of a rheostat con structed in accordance with my invention. Fig. 2 is a longitudinal sectional view on the line 22 of Fig. 1. Fig. 3 is a side elevation of the rheostat. Fig. 4. is a view in perspective of a modified form of one of the plates of the rheostat. Fig. 5 is a diagrammatic view clearly illustrating the connections between the rheostat and the contacts and source of electrical supply.

Referring by numerals to the accompanying drawings, 1 indicates a cylindrical metallic box or casing, the same being provided on its upper edge with a projecting flange 2 and vertical slot 3 in its face and on the interior of the wall with a vertical rib t. A circular cover 5 is adapted to be bolted to the flange of the casing 1 by means of suitable bolts 6.

Adapted to fit within the casing 1 is a series of disks or plates 7, the same being constructed preferably of fire clay, or analogous material, and provided with convolute grooves or depressions 8 extending from the centers of the disks to the edges thereof. These grooves extend approximately half way through the thickness of said plates. These disks are provided in their edges with semi-circular notches 9, which notches are adapted to be engaged by the vertical rib 4 on the interior of the casing]. Thus the plates will be held in a stationary position within the casing and not allowed to rotate. The plates are held together in pairs by suitable bolts 10, said bolts passing through the centers of the plates. Said bolts are provided on their screw-threaded ends with ordinary nuts 11, said nuts and the heads of the bolts being countersunk in the plates 7 so as not to contact with the not or head of the bolt of the adjoining plate. In constructing these plates, one end of a suitable wire or conductor 12 is looped around the body of the bolt 10, and then positioned in the convolute groove or depression Sin the plate 7, the outer end 13 of said conductor or wire extending a slight distance through the vertical aperture 3 in the casing 1. This being done, soft or plastic fire-clay is pressed into the convolute groove 8 above the conductor 12 and there allowed to harden and dry. Thus the conductor 12 will be thoroughly embedded in the plate 7.

Suitable conductors 14 are interposed be tween every pair of the plates and lead from the central bolts 10 to a point just outside the vertical aperture 3 in the casing 1. The conductors 12 so embedded and located in the plates 7 form the resistance coils of the rheostat.

In the modified form of plate shown in Fig. 4, said plate is constructed of fire-clay, or analogous material, and in rectangular form, the grooves or depressions therein extending in parallel lines. When the plates are so formed, the box or casing containing them must necessarily be rectangular in form also.

Referring now to Fig. 5, the diagrammatic view, 15 indicates a dynamo, 16 the conductors leading therefrom, 17 a switch-arm, and 18 the contacts which may be arranged in any suitable manner. The coils 12 are connected in series to form a proper resistance, and the contacts are connected by suitable conductors 19 to the resistance at different points in the length of said resistance, or to the ends 13 of the resistance coils and the conductors 14 that extend beyond and from the vertical aperture 3.

As shown in Fig. 5, the resistance is entirely cutout and the full current of the electricity passes directly through the dynamo 15, conductor 16, switch-arm 17 and the first one of the contacts.

Should the switch-arm be thrown to the fourth contact, or to the position shown by dotted lines, it will be seen how said current of electricity will be caused to pass through three of the resistance coils, thereby obtaining the desired result.

It will be plainly seen how, by adding a number of the plates having the resistance coils 12 embedded therein, any resistance desired may be obtained.

By forming the plates of fire-clay, which is as well known a suitable non-conductor, a rheostat may be simply constructed and at a very minimum cost.

What I claim is 1. A rheostat, comprising a cylindrical casing, a cover bolted to said casing, a series of fire-clay disks or plates in which are embedded suitable wire coils, bolts connecting each pair of said disks, and suitable conductors from said bolts to the outside of the cylindrical casing.

2. A rheostat, comprising a cylindrical casing provided with a vertical slot in its face, a

vertical rib on the interior of its wall, a suitable cover for said casing, a series of fire-clay disks located within said casing, said disk be ing provided with convolute grooves in their faces and semi-circular depressions in their edges, suitable conductors embedded in said convolute grooves or depressions, bolts securing the disks together in pairs, and conductors leading from said bolts to the outside of the casing.

3. In a rheostat, pairs of disks or plates of fire-clay or analogous material bolted together, said plates having embedded therein convolute conductors, and suitable conductors from the bolts to the edges of the disks or plates.

In testimony whereof I affix my signature in presence of two witnesses.

THOMAS W. SI'IELTON.

\Vitnesses:

C. K. JONES, M10. 0. HIGDON. 

